In order to provide communications between different networks, it is known to employ so-called media-gateways, which are devices that convert media input from one network into a form suitable for another network. For example, media gateways can be provided between a packet-switched network (e.g. an IP based network) on the one hand and a circuit-switched network (e.g. a PSTN) on the other hand.
Furthermore, it is known to functionally separate the control over the communications between the two networks connected by the media gateway from the media gateway, by providing separate control entities, which can also be referred to as media gateway controllers. It may noted that the media gateway and media gateway controller are functionally separated, which means that they can also be physically separated, but could also be located in the same network node.
The division into a media gateway (or media gateway node) and a media gateway controller allows an increased flexibility in arranging the communication networks, and e.g. enables the separation of hardware resources from logical software resources. This division can also be exemplified by the concept of a control plane and a bearer plane, where the media gateway is at the bearer plane and the media gateway controller is at the control plane.
A special situation arises if one of the networks connected to the media gateway is a circuit-switched network, and the communication via the media gateway is handled through a predetermined number of circuit-switched channels specifically associated with the media gateway. In other words, communications to and from said circuit-switched network over said media gateway are conducted over a predetermined number of circuit-switched channels assigned to the media gateway. If more than one media gateway controller is connected to the media gateway under consideration, then the circuit-switched channels associated with the media gateway are grouped, and respective groups are allocated to each media gateway controller, such that each media gateway controller can control communications between the two networks via the circuit-switched channels in the allocated group.
In such a situation there will be a 1-to-1 relation between a software resource in the media gateway controller, a physical connection to the circuit-switched network in the media gateway, and a channel identifier, which is used in the control protocol between the media gateway and the media gateway controller.